大鼠视网膜缺血-再灌注损伤后视觉传导通路中神经丝蛋白200的表达

Expression of neurofilament 200 in different sections of neurons of the visual pathway after retinal ischemia reperfusion injury

背景神经丝蛋白200（NF200）是特异性分布于神经元轴突内，维持神经元形态、反映其功能、检测轴突再生状况的一个间接指标。NF200是否参与了视网膜缺血-再灌注损伤（RIRI）后整个视觉传导通路的异常变化有待进一步研究。目的研究RIRI后各时间点大鼠视觉传导通路中视网膜、外侧膝状体、上丘脑及视皮质等部位NF200的表达。方法应用随机数字表法将40只SD大鼠随机分为RIRI1、2、3、4、6、8周组，伪手术组和正常对照组，每组5只大鼠。RIRI组采用前房灌注生理盐水法制作RIRI模型，以右眼为损伤眼；伪手术组仅行前房穿刺而不灌注生理盐水。于RIRI后1、2、3、4、6、8周处死大鼠，摘除大鼠眼球，并取外侧膝状体、上丘脑及视皮质组织制备冰冻切片，采用免疫组织化学法检测NF200在上述大鼠各部位神经元及轴突中的表达。结果大鼠RIRI1、2、3、4、6、8周组、伪手术组和正常对照组损伤眼视网膜神经节细胞（RGCs）层NF200的表达量（A值）总体比较差异有统计学意义（F=78．855，P=0．000），其中RIRI1周组NF200表达较正常对照组明显减少，差异有统计学意义（t=36．563，P〈0．01）。RIRI1周后可见损伤眼对侧外侧膝状体NF200的表达较正常对照组明显减少，差异有统计学意义（t=6．483，P〈0．01），而损伤4周、6周后对侧外侧膝状体NF200的表达较正常对照组明显增加，差异有统计学意义（t=2．904、4．313，P〈0．01）。RIRI1周可见损伤眼对侧上丘脑NF200的表达较正常对照组明显减少，差异有统计学意义（t=2．966，P〈0．05），2周对侧上丘脑NF200的表达较正常对照组明显增加，差异有统计学意义（t=7．397，P〈0．01）。RIRI2、3、4周后双侧视皮质NF200的表达较正常对照组明显增加，差异均有统计学意义（对侧：t=18．728、18．213、15．088，P〈0．01；同侧：t=8．690、5．704、7．805，P〈0．01）。结论RIRI可造成损伤眼的RGCs、对侧外侧膝状体、上丘脑及双侧视皮质神经元轴突的损伤。

Background Neurofilament 200 （NF200） is an indirect indicator of the specific distribution of axons. It reflects the condition of the maintenance of neuronal morphology. Whether NF200 is involved in the damage of the visual pathway after retinal ischemia reperfusion injury （RIRI） should be further examined. Objective The present study was to investigate the expression of NF200 in retinal ganglion ceils （RGCs） ,lateral geniculate nucleus （LGN） ,superior colliculus and visual cortex following RIRI. Methods Forty SD rats were randomized into the RIRI 1-,2-,3-,4-,6-,8-week groups, sham operation group and control group. Acute intraocular hypertension was induced in the right eye by anterior chamber perfusion of normal saline solution for 60 minutes to elevate the intraocular pressure to 110 mmHg. The animals were sacrificed at different time points for the preparation of the retina, LGN, superior colliculus and visual cortex sections. The expression of NF200 in RGCs, LGN, superior colliculus and visual cortex was assayed by immunohistochemistry. Results The expression level （A value） of NF200 in the RGCs was significantly different among the 8 groups after reperfusion （F = 78. 855 ,P = 0. 000） ,and that in the 1-week group was significantly lower than in the control group （ t = 36. 563, P 〈 0.01 ）. In the RIRI 1-week group, the expression of NF200 in the contralateral LGN in the experimental group was significantly lower than that in the control group （ t = 6. 483, P〈0.01 ）. In the 4-week group and 6-week group, the expression of NF200 in the contralateral LGN was significantly higher than that in the control group （t = 2. 904,4. 313, P〈 0. O1 ）. One week after RIRI, the expression of NF200 in contralateral superior colliculus in the experimental group was significantly lower than that in the control group （t = 2. 966,P〈0. 05 ） , and in the 2-week group, the expression of NF200 in the contralateral superior colliculus was significantly higher than that in the control group （t = 7. 397, P〈0.01 ）. In the 2-week group, 3-week group and 4-week group,the expression of NF200 in bilateral visual cortex was significantly higher in the experimental group than that in the control group （ contralateral i t = 18. 728,18.213,15. 088, P〈0.01 ; ipsilateral ： t = 8. 690,5. 704, 7. 805,P〈0. 01 ）. Conclusions RIRI can induce axonal damage of RGCs, contralateral LGN, superior colliculus and bilateral visual cortex neurons.